The overall objective of this project is understand the mechanisms whereby trophic factors such as NGF promote the differentiation, maintenance, plasticity, survival and repair of neurons. Past studies indicate that transcriptional regulation plays an important role in the NGF mechanism. However, our understanding of the identities and roles of the genes regulated by NGF is very incomplete. We hypothesize that 1) there are many known and unknown genes that are transcriptionally regulated by NGF that have yet to be recognized as such, 2) that such genes will be detected by the comprehensive SAGE analyses proposed here, 3) that such genes play major roles in the mechanism of NGF actions and 4) that such roles can be determined by deduction of function from sequence analysis combined with experimental manipulation of gene expression. The specific set of studies proposed here will thus seek to comprehensively detect and identify genes regulated by NGF and to test their functional roles in NGF actions. Four aims are given: (1) To carry out comprehensive analysis of NGF-regulated gene expression in PC12 cells by high-throughput SAGE analysis. (2) To Extend PC12 cell SAGE findings to neurons, i.e., to determine whether genes regulated by NGF in PC12 cells are also regulated in cultured neonatal sympathetic neurons and cultured adult sensory neurons as well as in neonatal sympathetic neurons in vivo. (3) To carry out functional analysis of NGF-regulated genes by evaluating multiple classes of NGF responses in cultured PC12 cells and neurons in which expression/activity of NGF regulated gene products is either enhanced or inhibited. (4) To Develop and disseminate (via the Web) comprehensive SAGE data bases of basally-expressed and NGF-regulated genes in PC12 cells and other neuronal systems. Understanding how neurotrophic factors like NGF work will provide insight into a wide variety of key brain functions and has the potential to lead to design of pharmaceutical agents for the treatment and prevention of a number of maladies affecting the nervous system